Data structure refers to a particular manner of organizing and storing data. In other words, data is structured in accordance with a particular data model or schema. In a database, for instance, a database definition (a.k.a. database model) specifies structure in terms of metadata that defines database objects. In relational database management system (RDBMS), for example, the metadata includes tables, views, functions, procedures, and other system objects. The metadata can also include reference data (e.g., zip codes, states, countries . . . ) that is stored in tables but is logically part of the definition. A database definition can be stored in various source and operational formats and deployed as a live database on a running database server, for instance.
A variety of applications exists that exploit the database definition to provide various tools or services including deployment, upgrade, comparison, navigation, and validation, among others. By way of example, tools exist that provide a visualization of the structure of a database.